The present disclosure pertains to a band for sealing between a boot and a block or tie which supports a rail of a railway track system.
Light rail, metro and subway lines around the world have recently been equipped with various non-ballasted track systems in order to reduce maintenance costs and to enhance performance. Many of these systems comprise a block or tie generally made of precast concrete. The block or tie is often held in a rubber boot with a resilient elastomeric pad placed between the base of the block or tie and the base of the boot. The boot is then encased in concrete or grout. The rubber boot is advantageous in that it allows deflection of the block under dynamic loads. It is also known to place a rail pad between the bottom of the rail and the top of the concrete block. The rail pad is helpful in mitigating the effects of higher frequency vibrations, whereas the resilient pad placed between the bottom of the concrete block and the bottom of the rubber boot serves to mitigate the influence of low frequency vibrations. Further information concerning such systems can be found in U.S. Pat. No. 6,364,214, the contents of which are incorporated by reference hereinto in their entirety.
It is also known to seal between the rubber boot and the block in order to retard the ingress of water and other fluids into the boot because such fluids could give rise to damage to the block, the boot, or both. To this end, it is known to position a band surrounding the top margin of the boot so as to provide a seal between the boot and the concrete block.
However, the known band is not optimized for retarding stray current from flowing between the rails on which the light rail carriage moves and the electrified third rail which powers the movement of the railway carriage. Stray current corrosion has been found to be a significant problem with direct current powered transit systems. In such systems, the railway carriage can be powered by, for example, 750 volts DC traction power supplied to the railway carriage through a pickup shoe in contact with a third rail located to the side of the track. The negative return from the car is through the car wheels and to the running rails. Thus, the running rails, which are supported on blocks encased in boots, are the primary source of the stray current.
Therefore, it is desirable to minimize the flow of stray electrical current through the running rails of the railway carriage. It would be desirable if the electrical isolation of the running rails from the ground is maximized. To meet these objectives, it would be desirable to provide a band encircling the joint between the rubber boot and the concrete block, which band maximizes the electrical isolation of the running rails in relation to the ground surface.